JPH04192811A - A/d converter circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a multi-bit A/D conversion circuit that obtains a resolution greater than the number of converters.

[Prior Art] FIG. 3 is a block diagram showing an example of a conventional A/D conversion circuit. In the figure, (1) is the front-stage analog circuit, (2) is the rear-stage digital signal, (3) is the reference voltage generator, and (5)
is a converter, and (8) is an encoder.

The reference voltage generator (3) generates a reference voltage for comparison in the comparator (5). Converter (5)
compares the analog signal from the previous-stage analog circuit (1) with the reference voltage from the reference voltage generator (3) and outputs a digital signal. Encoder (8) is converter (5)
The digital signal output from the circuit is encoded and the digital code is output to the subsequent digital circuit (2).

[Problems to be Solved by the Invention] In conventional A/D conversion circuits, when increasing the resolution of A/D conversion, it is necessary to increase the number of converters that constitute the A/D conversion circuit. However, there is a problem in that there is a limit to the increase in the number of converters due to problems such as heat generation and an increase in input capacity.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to improve the resolution of A/D conversion without increasing the number of converters constituting the A/D conversion circuit.

[Means for Solving the Problems] The A/D conversion circuit according to the present invention includes a converter that compares an analog signal output from the 378 section with a reference voltage generated by the reference voltage generation section, and an analog signal output from the 378 section. By providing a subtracter that subtracts the reference voltage generated in the reference voltage generator from the signal, and a multiplexer that switches the analog signal output from the subtracter using the digital signal output from the converter, the resolution of the A/D conversion circuit can be improved. is the product of the voltage determination circuit resolution, and the resolution can be improved.

[Function] The A/D conversion circuit according to the present invention can improve the resolution of A/D conversion without increasing the number of converters making up the A/D conversion circuit.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, (3) is a reference voltage generation section, (4) is a 378 section,
(5) is a converter, and (6) is a subtractor.

(7) is a multiplexer, and (8) is an encoder.

Note that components not related to this invention are omitted.

First, the inside of the first voltage determination circuit (9) will be explained.
Part 8 (4) holds the analog signal from the previous stage analog circuit (1) for a certain period of time. The analog signal output from the 378 section (4) is 0 to 4x.

See Figure 2(a). The reference voltage generator (3) generates a 2x reference voltage. The subtraction part (6) is 3 shown in FIG. 2(a).
The reference voltage 2x generated by the reference voltage generating section (3) is subtracted from the output analog signal of the 78 section (4).

The converter (5) compares the analog signal from the 378 section (4) with the reference voltage from the reference voltage generating section (3) and outputs a digital signal. The multiplexer (7) is switched by the output of the comparator (5). If the reference voltage generation section (3) is higher than the 378 section (4), the switching is made to the 378 section (4) side, and in the opposite case, it is switched to the subtraction section (6) side. The output range of the multiplexer (7) is 0 to
It is 2x. The output of the multiplexer (7) is shown in Figure 2 (b).
) Reference 0 Next, the second voltage determination circuit (10) will be explained. The 378 section of the second voltage determination circuit (10)
The analog signal from the multiplexer (7) in the voltage determination circuit (9) is held for a certain period of time. The analog signal output from the 378 section (4) is 0 to 2x. The reference voltage generator (3) generates an X reference voltage. converter
(5) compares the analog signal from the 378 section (4) with the reference voltage from the reference voltage generation section (3) and outputs a digital signal. The encoder (8) is connected to the first voltage determination circuit (9
) in the converter (5) is connected to the second voltage judgment circuit (1
0) encodes the digital signal from the converter (5) and outputs the digital code to the subsequent digital circuit (2).

Note that a large number of converters and subtraction units may be arranged in parallel.

[Effects of the Invention] As described above, according to the present invention, by using a subtracter and a multiplexer, the resolution of A/D conversion can be increased without increasing the number of comparators constituting the A/D conversion circuit. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an A/D conversion circuit according to an embodiment of the present invention, FIG. 2 is a graph showing each signal waveform, and FIG. (b) is a graph showing the output signal of the multiplexer in the first voltage determination circuit, and FIG.
It is a block diagram of a D conversion circuit. In the figure, (1) is a front-stage analog circuit, (2) is a rear-stage digital circuit, and (3) is a reference voltage generation section. (4) is the 378 unit, (5) is the converter, (6) is the subtraction unit, (7) is the multiplexer, (8) is the encoder, (9) is the first voltage judgment circuit, (10) is the second A voltage determination circuit (11) is an embodiment of the present invention.
/D conversion circuit (12) is a conventional A/D conversion circuit. Note that the reference numerals in the middle of FIG. 7 indicate the same or corresponding parts.

Claims (1)

[Claims] S/H (Sam) that holds the input analog signal for a certain period of time
a reference voltage generation section that generates a reference voltage, a subtraction section that takes the difference between the S/H section output S and the reference voltage from the reference voltage generation section, and a subtraction section that calculates the difference between the S/H section output S and the reference voltage generation section; A voltage determination device comprising a comparator for comparing reference voltages from the subtractor, a multiplexer for switching between the subtraction section output and the S/H section output using the comparator output, the S/H section, the reference voltage generation section, the subtraction section, the comparator, and the multiplexer. A which connects circuits in multiple stages and includes an encoder that encodes the digital signal from the above-mentioned converter.
/D (Analog to Digital) conversion circuit.